Solenoid problem? Check valve? Dyno chart inside
 

First dyno session ever the other day, just a couple back-to-back runs

Power was lower than I was expecting/hoping and I'm curious about what's going on with the top of the curve
The AFRs are from the shop's tail pipe sniffer, so not super accurate. When the guy let off the gas at the end of each pull, there was a puff of unburned fuel that came out the exhaust

Modifications:
Intake/exhaust/SMIC/PFC/HKS Twinpower
Boost is set to 11.5psi on stock sequential twins. Apparently it's not an issue specific to my map or the PFC settings
I just tuned what I could on the highway (using a wideband and Chuck's notes), which obviously didn't show the power level bouncing at the end

Any ideas what would cause that?

Knock never went over 30 fwiw
When my LC1 was working last week, it read boost as having ~11.5 AFR +/- 0.3

Woah....that's pretty scary looking. What did the car sound like when you were doing the dyno?

It's interesting that on the primary turbo the precontrol duty cycle is jumping all over the place as well. Maybe it's a problem that affects operation of both turbos.

I couldn't tell anything was wrong by the sound
If you look at the RPMs in the datalog, they went up steadily. It was the power and boost that wavered

Arghx, any expertise you could give would be appreciated, otherwise I might be stuck throwing money at it :lol:

I would first go to a mechanical valve for boost control to eliminate the PFC ebc system.
If the oscillating boost still persists then you have other problems.

A single run log of 2000 - 5000 rpm of advanced functions and your map would be very helpful.

I've seen something similar before on another car many many years ago.

Where/what are you using to measure boost? What tapping point physically on the engine are you taking these readings from?

Do you want a copy of the log itself? Or an image of a map watch, or a chart of certain parameters?

The Pfc is using the stock system to modulate boost, although I can try that. Boost is measured via the stock sensor in stock position
Car is JDM with 34k Km FWIW. Owned it 5 or 6 years



Edit: If I unplug the electrical from the solenoids, should that make the system run steady boost at wastegate pressure? That might be a faster way to rule out the ECU control, if so

you should be able to unplug the stock precontrol and wastegate solenoids. they bleed air away from the wastegate actuators so that the actuators open later (for higher boost). make sure you take a log when you are running that way.

Here's a quick 3rd gear highway pull
Same thing as on the dyno. The chart is attached

On a second pull I tried increasing wg duty from 56/64 to 70/80 and the car behaved the same way, just with slightly higher boost.

I didn't see your confirmation regarding unplugging the solenoids until now, so I haven't yet tried that

If the PC% and WG% are on the same scale then I think the problem is because the boost control feedback is too aggressive. I agree with cewrxr1 and arghx, unplug the PC and WG solenoids so the ECU is not controlling boost.

I'm not familiar with how to adjust boost control on the PFC, but if you have some way to set the WG duty to 30% and disable feedback that is what I would suggest trying after you plug the solenoids back in.

unfortunately the PFC doesn't have any gain setting or "feedback speed" like an AVCR.

You are sure you only have unimportant vacuum lines like BOV hooked up to the nipples on the primary runners on the UIM right where it meets the LIM?

On my FC with FD UIM I first had my MAP sensor hooked up there and it ran like your car.

Checked my data logs and there were pressure fluctuations 2-3psi (I didn't even have a turbo installed on car yet).

I figured it was dynamic intake pulses and moved the MAP sensor line to stock location just behind the throttle body and car ran smooth on top end and data logs showed a much smoother almost 0 psi signal.

Don't use these for anything important.

https://cimg8.ibsrv.net/gimg/www.rx7...8421acfe31.jpg

Got another log done, this time with the 2 solenoids disconnected
Everything looks to be acting the way it should
The MAP sensor is connected by the TB, which I assume is the stock position. The only thing connected on the UIM (on one of the ports pictured above) is the recirc valve (?) by the air intake. I assume this to be stock as well

So the turbos are good, but something is wrong with the turbo control system
Any suggestions on how to narrow down where the fault lies, without removing the UIM to access the solenoids?

:icon_tup:

My opinion is to just ditch the electronic control of WG and Pre-spool and go to a Hallman Pro-RX on each.

You can easily fine tune it so the transition is seamless and it stays that way.

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I agree!

Back in the days of the reprogrammed stock ecus, my turbos would not make more boost with the ecu than stock. I then added two mechanical valves. One to control bleed-off for boost control and the other to get the flattest transition boost.

Then I was able to get the boost I wanted.

I want to see your map and log!
Are you sure that map is OK?

Email it to me - cewrx7r1@yahoo.com .

I emailed you!

I found my old logs from when I originally tuned the car, 5 years ago

Boost was stable then, PC and wg worked properly and my wideband worked properly.
The only changes since then are that I installed a twinpower and my wideband sensor failed.
Plus 5 years of wringing it out :lol:
My car is garaged for the winter now, but in the spring I'll try removing those and getting a new log if I cant figure out anything else

I understand you are trying to avoid removing the UIM, but have you thought about replacing all your vacuum lines? And while at it, testing all your solenoids?

:lol: Yes indeed
Over the winter, the longer it sits unfixed, the more I want to spend money on it to ensure it works properly as soon as I can take it out of the garage again

So I have new solenoids, new silicone vac line, and new viton check valves waiting to go on
I'll test the solenoids before I replace them, but they're getting replaced regardless

Where did you get the solenoids from and the viton valves?

Viton check valves from DaleClark
Solenoids from MAC 3 Port Electronic Boost Control Solenoid Valve DC12V 5.4W 35A-AAA-DDBA-1BA | eBay

Thanks a lot!!